This invention relates to a deep sea transhipper for the transfer of bulk cargo between vessels or between port and a vessel. This invention also relates to a method of material transfer.
It is trite that many harbours without deep water docking facilities are either completely excluded from participating in the revenue capable of being generated by bulk material loading, or if not completely excluded, are confronted with diverse costly logistical and environmental concerns. The logistical concerns may include the establishment of deep sea berths, conveyors with offshore tressels and frequent dredging, all with concomitant environmental and noise pollution, disruptions, and installation and maintenance costs.
One solution has been to load cargo onto a shallow draft barge which then travels out to deep water, is moored alongside the cargo ship and then off-loaded. Many barges however lack self off-loading capabilities. Generally, even those barges with self off-loading capabilities have no, or limited means to discharge the material into the cargo holds of a cargo vessel at deep sea.
Moreover, even where a port has deep draft loading facilities, it may not always be possible to berth the deep draft cargo vessel within the reach of the port""s loading facilities. A means would then be required to transfer the material from the port to the cargo vessel, such as the rigging of a conveyor and a tressel.
In circumstances such as inclement weather and high energy wave action, the utilization of a barge for deep water loading ma be undesirable or even impossible. The design features of but a few barges would provide sufficient stability in such circumstances for a transfer of the material to the cargo Vessel.
Again, few barges, if any, comply with international standards requirements for deep water vessels, such as lop relating to self-sealing bulkheads. Generally, the design specification of barges exclude such features, as their hoppers extend into the bulkheads.
It is an object of the present invention to alleviate the abovementioned difficulties and to provide a transhipper which is capable of being employed not only as a port to ship transhipper, but also as a deep sea, port to ship or even ship to ship transhipper.
According to the invention there is provided a self-loading, self-discharging, bulk cargo transhipper which comprises of a buoyant vessel, bulk material receiving system, a bulk material distribution system and a bulk material holding system.
The transhipper may be towable by another vessel such as a tug, or it may be equipped with self-propelling and steering means.
The buoyant vessel, which provides a platform for the material receiving system, the material distribution system and the material holding system, may also make provision for one or more ballast chambers for receiving water as ballast inside the buoyant vessel. The buoyant vessel may also provide for hydraulic, electrical and generator rooms to house operating equipment, and it may also allow for crew quarters and an operator""s cabin.
According to the invention the material receiving system may comprise of a listing conveyor, comprising a pocket transfer conveyor and, a sea marine leg, for raising material to be unloaded from an outward source, such as a barge, to the transhipper, and a means for slewing or luffing the lifting conveyor relative to the outward source to be unloaded. The material receiving system further comprise; of a hopper, which may be mounted on the bow of the transhipper, and which serves to receive material raised to the transhipper by the lifting conveyor, or which may serve to receive material delivered to the transhipper direct from an outward source, the latter which may be a port or cargo vessel. The said bow hopper is configured to allow for the gravity discharge of the material, received from the outward source direct or raised by the lifting conveyor and discharged into the bow hopper, through a discharge opening onto a loading conveyor means for further conveyance of the material to the material distribution system of the transhipper.
According to the invention, the material distribution system of the transhipper comprises a reclaim conveyor, a C-loop vertical conveyor, a distribution conveyor and a distribution boom, the latter which is supported on a support tower. The reclaim conveyor is the means by which material discharged from the material receiving system is transferred to the vertical conveyor of the material distribution system. The material is raised by the vertical conveyor to the distribution conveyor from whence it is conveyed for discharge to an outward destination, for example, a cargo vessel, or for discharge directly into the material holding system of the transhipper.
The material distribution system of the transhipper also allows for a means whereby the boom of the material distribution system is capable of luffing and slewing to facilitate distribution of the material relative to the position and height of the outward material destination. The material distribution system of the transhipper may also provide for a shuttle means to extend the horizontal reach of the boom conveyor.
Further, according to the invention, the material holding system of the transhipper comprises of a main hopper, longitudinally affixed to the buoyant vessel in a raised position by means of pillars or columns, for the holding of material which is to be transferred to the outward material destination. The main hopper of the material holding system of the transhipper is also configured to allow for the gravity discharge of material through a number of discharge openings onto the reclaim conveyor. The main hopper also comprises a means to control the flow of the material through the discharge openings of the main hopper. In an elaboration of the invention, the main hopper of the material holding system of the transhipper is divided into a plurality of holds, for example, to provide for the segregation of material in separate holds according to, for example, type or weight
In a further elaboration of the invention, the material distribution system of the transhipper may also comprise a reversible tripper conveyor, mounted longitudinally above the main hopper of the transhipper, to receive material discharged by the boom conveyor of the material distribution system for further distribution of the material by the tripper conveyor into the said holds of the main hopper.
According to the invention there is also provided a method to transfer material from an outward material source to an outward material destination and a further method to provide a self-loading, self-discharging, deep sea vessel for the transfer of cargo from an outward material source to an outward material destination, the latter which may be at deep sea.
The first said method of operation comprises of the steps of securing the bow of the transhipper to the outward material source and securing the stern of the transhipper to the outward material destination, which may be a cargo vessel. The material from the outward source is discharged directly into the bow hopper of the transhipper or collected by the lifting conveyor of the transhipper and discharged into the bow hopper. The material is discharged from the bow hopper onto a loading conveyor by which it is conveyed to, and discharged onto the reclaim conveyor which, in turn, transfers the material to the vertical Conveyor. The material is raised by the vertical conveyor and discharged onto the boom conveyor of the distribution boom, which is slewed over the cargo hold of the outward material destination. The material is then discharged into the said cargo hold from the boom conveyor.
Further according to the invention, a second method of operation is provided comprising the steps of directly receiving or collecting material from an outward source as described in the first method above. The material so received by the material receiving system of the transhipper is discharged onto the reclaim conveyor, raised by the vertical conveyor and discharged onto the boom conveyor. The material discharged onto the boom conveyor is, in turn, discharged directly into the main hopper of the transhipper or onto the reversible tripper conveyor for further distribution into the holds of the main hopper of the transhipper. The material is held in the main hopper of the transhipper whilst the transhipper is towed, or whilst it propels itself to the outward material destination. Having reached the outward destination, which may be a cargo vessel, the transhipper is moored alongside the cargo hold of the cargo vessel. In a further elaboration of this method, the transhipper may be moored diagonally to cargo hold of the cargo vessel with the stern of the transhipper facing the cargo vessel. In either case, the boom of the material distribution system of the transhipper is slewed over the cargo hold of the cargo vessel. The material held in the main hopper of the transhipper is then discharged onto the reclaim conveyor through the discharge openings of the main hopper of the transhipper. The material is then transferred to the vertical conveyor of the transhipper, raised and discharged onto the boom conveyor. The material is then discharged by the boom conveyor into the cargo hold of the cargo Vessel.
Further objects and advantages of the invention will become apparent from the description of the preferred embodiment of the invention below.